I don't glue the floor of my bottom boards. If the bees don't like the small gaps that might appear as the wood dries more they can fill the cracks in. I would imagine if that were a problem, though, no one would use screened bottom boards. In my opinion, the aesthetics of a hive and it's components are merely to keep the beek happy. Bees live in holes in trees, logs, shrubs, etc... I'm pretty sure they don't care about a cracked floor.